Add a mojo interface for AccountId

ash/mus/test/wm_test_base.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ash/mus/test/wm_test_base.h"
 
 #include <algorithm>
 #include <vector>
 
 #include "ash/common/session/session_controller.h"
@@ skipping 171 matching lines @@
 }
 
 void WmTestBase::SimulateUserLogin() {
   SessionController* session_controller = WmShell::Get()->session_controller();
 
   // Simulate the first user logging in.
   mojom::UserSessionPtr session = mojom::UserSession::New();
   session->session_id = 1;
   session->type = user_manager::USER_TYPE_REGULAR;
   const std::string email("ash.user@example.com");
-  session->serialized_account_id = AccountId::FromUserEmail(email).Serialize();
+  session->account_id = AccountId::FromUserEmail(email);
   session->display_name = "Ash User";
   session->display_email = email;
   session_controller->UpdateUserSession(std::move(session));
 
   // Simulate the user session becoming active.
   mojom::SessionInfoPtr info = mojom::SessionInfo::New();
   info->max_users = 10;
   info->can_lock_screen = true;
   info->should_lock_screen_automatically = false;
   info->add_user_session_policy = AddUserSessionPolicy::ALLOWED;
   info->state = session_manager::SessionState::ACTIVE;
   session_controller->SetSessionInfo(std::move(info));
 }
 
 
 }  // namespace mus
 }  // namespace ash